THE BOOK--Playing The Percentages In Baseball

I’d peg Strasburg for a 3.75 ERA this season, so a 2.50 ERA on the good side would be roughly 5.00 on the bad side.  Though I probably should skew that forecast more towards the poor performance; a 2.50 ERA would be an incredible performance.

I guess I should have asked this beforehand: Are we talking for his career, or if he appears in 2010? I voted under the latter assumption, but the results distribution seems to indicate people may be voting for either possibility.

Well, I voted for 5.50 and in retrospect I think that might be too low. Great poll question though.

Even if you think his true-talent is a 3.00 ERA, there are plenty of reasons why it is more likely he will post a 5.50 than a 2.00 For one thing, if he outperforms his true-talent early, he will keep getting innings which will naturally regress toward his true-talent making it less likely he will post that 2.00. However, if he performs worse than his true-talent (injury? luck?) he will not get the opportunity to regress.

Just my take anyway.

After 39 votes, the average is 4.69.  That is, you guys think it’s just as likely he will post a 2.50 or better ERA as he is to post a 4.69 or worse ERA.

The midpoint, for whatever that is worth, is 3.60.  That number is 84% of the league average.

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The standard deviation of the high-mark is 0.55.  This means that you guys said that the high-mark is 4.69 +/- 1SD of 0.55.

After 69 votes, average is 4.82 and 1SD = 0.56.

That sets the midpoint at 3.66, which is 85% of the league average.

I misvoted; Was thinking 5.75, but clicked 2.75

Every above-average pitcher has non-trivial chance (much better than based solely on his talent level) to go all Gibson on the league for first dozen or so Major League starts, until hitters see him and make the adjustments. There is a chance that he would get into majors in late June/early July, giving him around 10-12 starts before September, where he will typically see weaker than normal lineups. I would say that Strasburg has better chance of having under 2.5 ERA than pitchers like CC, Lincecum, Felix,… Of course, he also has better chance of posting 5+ ERA. That’s another way of saying that Strasburg has much wider error bars than established pitchers.

Felix was 2.49 last year.  Too bad we didn’t make the bet a year ago.